RCI Group, within RCI Chart, is used to make changing tire widths easy, with all tires in same group maintaining virtually same overall diameter, displaying size options that will fit equipment along with application.

Below is Example of Group 46 Alternate Sizes:

As shown above, in Group 46 (73″ overall diameter):

20″ Rows use sizes 320/90R50 & 380/90R46

30″ Rows use sizes 420/80R46 & 480/80R42

38″ Rows use sizes 520/85R38

Broad Acre or Flotation uses sizes 650/65R38 & 800/65R32.

RCI Charts

Below are two great RCI Charts I like to use from Goodyear Titan & Firestone Ag:

To determine alternate sizes for tractor, here’s what to do using Goodyear Titan’s user friendly RCI Chart shown below:

Determine Original Equipment Size(s) (E.g. 380/90R46)

Find Group Number for Front and Rear Axle on RCI chart (E.g. Group 46)

Determine Application (E.g. Flotation)

Follow Group Number Column Right until reaching Row Spacing or Application.

Why not give the RCI Index Chart a try?

It is important to note that some equipment cannot use all alternate sizes listed for a variety of reasons including space limitations, drivetrain limitations, and other factors.

All information is provided in this blog solely to provoke thought. All deductions made from information on this site must be confirmed by Certified Ag Tire Dealer before use. Ag Tire Talk does not recommend anyone conduct tire service work with exception of Certified Ag Tire Dealer Professionals.

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4 Responses to “Ag Tire Size Options: RCI Chart”

I have a spray coupe with rear duals 340/85R24. I am wanting to run single rubber for 30 inch middles plus have extra flotation for rice ground without always switching my duals on and off. Will a 380/85R24 fit on the same rim?